Apple LED Display Black Screen and Sound going crazy

So, i am using a LED Apple DIsplay 24 as a second monitor on my Windows computer, some times the screen go black for no reason, the computer still recognize it, the sound works fine and the usb ports work also fine. In order to get back my screen, i need to unplug from the power sourceand plugin it back, have you a solution for that ?

And second problem. When i boot my computer with the usb pluged in, the soud from the display go crazy like an ultrasound that won’t go off until i pluged out the usb, so i could not use the internal speakers.

Any help with these problems will be gratefull thanks